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UNTTED PATENT @FFICE..

BERNARD r. rnnnnnn, or rrpwnsr, wvo vrnve, essieno t or ONE-HALF o W. J. QH L OF TEEBMOPOLISI WY- M PatentedDec. 16, 1 919.

NDE AMEB- ,3 1118 Specification of Letters Patent.

Application filed November 12, 1918. Serial No. 262,230.

To all Whom it may concern Be it known that I. BERNARD F. FEEL- )mw, a citizen of the United States, residing at Midwest, in the county of Hot Springs and State of Wyoming, have in rented certain new and useful Improvements in Underreamers, of which the following is a specification.

This invention relates to boring tools of the class commonly known as under-creamers and used in the construction of deep wells to enlarge the bore thereof beneath an inserted casing which exteriorly is .of'

greater diameter than the bore.

It is the primary objectdof my invention to provide a tool of the characterdescribed which is of simple, strong and durable con? struction and which includes an arrangement of parts for holding its cooperative bits or cutters, which efiectively insures against their disconnection or displacement and permits of their solid and reinforced construction without bolt-holes, key-ways or other weakening passages or recesses which in tools of this type at present in common use, are often the cause of breakage.

The above and other objects all of which will fully appear in the course of the following description I attain by the construction and arrangement of parts shown in the accompanying drawings in which? Figure 1 is a sectional elevation of my improved under-reamer in its voperative position in a well-bore,

Fig. 2, a longitudinal section of the tool taken on the line 22, Fig.1,

Fig. 3, a transverse section taken on the line 33, Fig. 1, and

Fig. 1%, a perspective view of one ,of the bits of the tool.

Referring to the drawings, the reference character 2 designates the stock of the tool which for the purpose of assembling the interior working parts of the same, is composed of a body section 3 and a cap-section 4 fastened together by a number of countersunk cap-screws 5.

The body section of thestock is hollowed to provide two recesses 6 of circular section to receive the correspondingly formed knuckles of the bits 13 hereinafter to be described, a longitudinal channel 7 and a therewith continuous chamber 8 for the bar and spring provided to yieldingly' hold the bits in their operative position, and a recess ,9 the walls 10 of which flare from the firstmentioned recesses to the working end of the stock to provide a space for the movement of the shanks of the bits by which their before-mentioned knuckles are connected with their cutting-heads.

The two sections of the stock have furthermore at opposite ends of its recesses 6, circular seats 12 to receive trunnions formed at the corresponding ends of the knuckles of the bits.

Each bit 13 is formed of a single piece of steel and composed of a cutting head 14 having a rounded cutting edge 15 at its lower end, a? knuckle 16 which is rounded to turn within the respective recess 6 of the stock, a shank 17 of reduced width which connects the head with the knuckle, and trunnions 18 which project oppositely fromthe ends of the knuckle and are fitted in the seats 12 at the corresponding ends of the recess in which the knuckle has its movement.

At the juncture of the shank with the head of the bit a shoulder 19 is formed which in the use of the tool abuts against the lower end of the stock as will hereinafter be more fully explained.

The .two'bits of the tool in their operative position extend divergently with relation to each other as shown in Fig. 1 of the drawings in which "position they are capable of moving together under stress against the pressure of a coiled spring 20 which acts upon a headed bar 21 of angular section which is slidingly fitted in the channel 7 of the stock.

The outward movement of the bar is lim-.

ited by engagement of its head with a shoulder between the end of the channel and the therewith continuous enlarged chamber 8 which is occupied by the coiled spring 20.

The bar has a tang 22 which extends into' walls of the recess in which they have their movement, and their shoulders 19 abut against the lower end of the stock.

It will thus be seen that the impact of V the bits upon the breast of the work is re ceived by the stock and that the more fragile parts of the operating mechanism are'relieved from incident shocks and stress.

In the use of my improved tool, the stock carrying the operative parts assembled as shown, is attached to the lower end of the drilling stein by means of the usual taper tool screw joint, in the same manner and occupying the same relative position as the regular drilling bit, the tool thus joined together being suspended from a rope, or drill ing cable, by means of which they are lowered into the well bore which in Fig. 1 of the drawing is designated by the reference character A.

After a well is sunk to a considerable depth, its wall is usually secured against caving by the insertion of a tubularcasing B.

In order to continue the boring of the well to a greater depth it is necessary to en large the bore beneath the casing so as to permit of the latter being driven downwardly and it is for the purpose of producing this enlargement that the reaming tool of the present invention is employed.

Premising that the bore in size equaling the interior diameter of the casing, extends beyond the lower end thereof, the casing is raised about six feet above its resting position at the point in the bore commonly called the shoulder at which point the diameter of the bore has been reduced from size of outside diameter to that of the in side diameter of the casing, and the reamer is lowered in the bore to the point of the shoulder, above referred to, after its bits are loosely fastened together by somestrands of rope or other easily ruptured fastening means.

After the lower end of the stock has reached the position in which the cutting edges of the bits engage the surface of the bore, beneath the casing, the tool is moved up and downwardly and-at the same time rotated by means of natural twist of the rope from which it is suspended. At the first blow of the tool against the wall of the bore beneath the casing, the fastening breaks and the heads are caused to separate by the pres sure of the spring.

By repeated up and downward motions and rotations of the tool the ground beneath the casing is reamed as shown in Fig. 1 of the drawings, to a diameter substantially equal to the exterior diameter of the casing, it being understood that the displaced earth is constantly removed from the hole by the means ordinarily employed for this purpose.

It will be readily seen that the solid con struction of the bits and the means by which they are pivotally mounted in the stock, se cures them against disconnection and dis placement and that the chances of their breaking by impact with the breast of the hole upon which they work, are reduced to the minimum by engagement of the shoulders on their heads with the end of the stock, which relieves the knuckles by which they are pivotally held in the stock as well as the bar which yieldingly holds them apart from the rebound oi. their cutting action.

Having thus described my invention what I claim and desire to secure by Letters-Patent is:

1. An under-reamer comprising a stock having recesses of circular section and trunnion-seats at opposite ends thereof, out wardly projecting bits having knuckles rotatably fitted in the recesses and trunnions in the respective seats, and spring-pressed means engaging the knuckles to yieldingly maintain the bits in their projecting position.

2. An under-reamer comprising a stock having recesses of circular section, bits having cutting-heads extending outwardly from the stock, knuckles rotatably fitted in the recesses, and shanks connecting the knuckles with the respective heads, in engagement with convergent surfaces of the stock, and spring-pressed means engaging the knuckles to yieldingly maintain the bits in their pro jecting position.

3. An underreamer comprising a stock having recesses of circular section, bits having cutting heads extending outwardly from the stock, knuckles rotatably fitted in the recesses, shanks of reduced width, connecting the knuckles with the respective hea J, in engagement with convergent surfaces of the stock, and shoulders at the uncture ot the shanks with the respective heads, which abut against a superposed part of the stock, and spring-pressed means engaging the knuckles to yieldingly maintain the bits in their projecting position.

In testimony whereof I have atlixed my signature.

BERNARD F. FEHLMAN. 

